#!/usr/bin/env python3

import sys

def go(x, y):
    i = next((i for i in range(len(x)) if x[i] + y[i] >= 10), -1)
    if i < 0: return "0"
    while i > 0 and x[i-1]+y[i-1] == 9: i -= 1
    return (''.join(str(9 - d) for d in x[i:-1]) + str(10 - x[-1])).lstrip('0')

x = list(map(int, sys.stdin.readline()[:-1]))
y = list(map(int, sys.stdin.readline()[:-1]))
d = len(x)-len(y)
if d > 0: y = [0]*d + y
else: x = [0]*(-d) + x
A = go(x, y)
B = go(y, x)
print(A)
# print(min( (len(A), A), (len(B), B) )[1])